Hello. I need to purchase an 18-200mm lens and I want to buy the Nikon
18-200 VR but now Sigma has come out with an 18-200mm OS HSM at half the price. Does anyone know which one is a better lens. I'm shooting portraits and weddings.

The Nikon is slightly faster at the telephoto end at f/5.6 vs the f/6.3 of the Sigma so this means the Nikon would be slightly faster across most of the 18-200 range allowing you to get marginally faster shutter speeds.

The Nikon is better built, has a higher quality and slightly more effective stabilisation but costs quite a bit more so you will have weight out the advantages against the extra cost. Cost aside though, it is the better lens.

Like pqtips says ( ) this is probably the wrong place for this question and you'd be better off posting in the Nikon or Sigma section.